To be frank, and I don't mean to sound unprofessional or anything...but I would tell him where to stick it.
I just paid for a normal '04 hatchling. The gentleman I bought it from hasn't shipped it yet because it was 9 degrees outside in my state the other night. He felt it would be too cold, and I agreed.
The person who shipped you the snake should have waited to ship if he thought it was too cold, not loaded the poor snake up with heat packs. His irresponsibility led to the snake's death.
Sure, he didn't specify live arrival guarenteed, but come on! When you buy a snake, you EXPECT live arrival. You don't pay top dollar for a cadaver.
You paid the shipping, and I would leave it at that.
The real loser is the poor dead snake who paid the highest price of all.